Ender 3 Pro Bed Leveling Test

This is a simple bed leveling test I designed to help visualize areas with poor bed adhesion or other extrusion issues caused by a warped / un-level bed. It's a simple 0.2mm high model that is intended to print as one layer and will fill the entire build volume.
This model was inspired by the default leveling test that comes with Anycubic's Chiron printer, but with a couple of improvements:

* The test print has less overall circles in it with thicker lines to help with bed adhesion during the test.
* The outer corners of the bed were never tested by the original design due to the shape, so I've added some circles in the corners to show the level of ALL parts of the bed. I've noticed these areas can be tricky to get right, so it helps to test them together.

EDIT: Fixed an issue with the thickness of the model not working with Cura 4.9.1. It's been increased to 0.4mm thickness, but will still print as 1 layer when set to 0.2mm layer height.